Method of encapsulating coils

ABSTRACT

A method of encapsulating conductive coils, including coating the coil with a refractory suspended in a volatilizable organic carrier, heating the coil to volatilize the carrier and leaving a film residue of refractory, and potting the coil in aluminum or the like by pouring molten metal around the coil. The disclosed device includes two copper coils wound in the same direction about common axes and an aluminum body completely encapsulating the coils.

1 METHOD OF ENCAPSULATING COILS FIELD OF THE INVENTION The disclosedmethod is particularly adapted to encapsulating electrically conductivecoils in a metal body, wherein the coils may be partially dissolved orwashed during casting or potting. The article of manufacture is amagnetic field collecting device, particularly suitable for fuel savingdevices.

SUMMARY OF THE INVENTION A method of encapsulating conductive coils,such as copper, in aluminum or-the like, wherein the coils are firstcoated with a powdered refractory providing elec-' trical insulationforthe coils and preventing washing or dissolving of the coils duringpotting. The coils are coated-with the refractory by first coating thecoils with a volatilizable organic carrier having powderedrefractory-s'uspended therein and heating the coils to substantiallyvolatilize the carrier and leaving a thin coating of the refractory. Thecoil is then encapsulated in alumi num by pouring the molten aluminumaround the coil and finally cooling the metal, forming an aluminum body.

In the preferred method; of this invention, the coils are formed bywinding conductive wire around an aluminum arbor or the like. The coilsare coated with a powder refractory, such as TiO or SiO suspended in anorganic carrier, such as a water soluble acrylic. The coils are placedin a mold on the arbor and the molten aluminum is poured around thecoils in the mold, forming the aluminum body integral with the arbor.

The preferred article made by the above process includes two coppercoils wound in the same direction about parallel axes and an aluminumbody encapsulating the coils. The device is utilized to induce orcollect a magnetic field in a fuel saving device and the aluminum bodyhas been found to improve the effectiveness of the devicel BRIEFDESCRIPTION OF THE DRAWINGS FIG. I is a topperspective view of the moldutilized in the method of this. invention with the coils in place;

and

FIG. 2 is a top elevation of one embodiment of an article formed by themethod of this invention.

DESCRIPTION OF THE INVENTION The method'of this invention wasparticularly developed to encapsulate a plurality of conductive coils,such as copper, in insulated relation in a metal body. Such a device isutilized ina new system adapted to improvethe engine efficiency of anautomotive engine or the like by impressingunidirectional magneticfield" across the engine. The disclosed device is retained adjacent asource of pulsatingDC current, such as an automotive ignition coil, anda-magnetic field is thereby induced in the coils.'lt has now beendiscovered that encapsulating the coils in aluminum substantiallyimproves the efficiency of the system, apparently by concentrating orcollecting the magnetic field in the coils.

' The method 'of this invention is however not limited to this deviceand has other important applications.

In the disclosed method, the coils are encapsulated in a conventionalvertical mold 20 having an internal cavity 22 configured to form thedevice, as shown in FIG.

' and magnetic field in the coils l. The coils 24 are supported inspaced relation within the mold cavity on arbors or cylindrical pins 26.The arbors are preferably formed of the same material as theencapsulating material, which in the disclosed embodiment is aluminum.In the preferred embodiment of the engine efficiency system, thedisclosed device includes two copper coils wound inthe same direction onparallel axes. The coils 24 are left hand windings having copperconnectors 28. The connectors in the disclosed embodiment areconventional copper caps used to connect the coils in the engineefficiency system.

The coils in the preferred embodiment are coated with a thin layer ofpowdered refractory prior to encapsulation. The'powdered refractoryprovides electrical insulation for the coils and prevents surfacewashing or dissolving of the copper coils by the molten aluminum duringencapsulation. The coils are preferablycoated with the refractory byfirst coating the coils with the refractory suspended in a volatilizableorganic carrier or binder and then heating the coils to substantiallyvolatilize the carrier, leaving a thin residue ofthe powdered refractoryand sufficient binder to retain the refractory coating. For example, thecoils may be dipped in a sili- I cone oil having SiO suspended thereinand heated in a conventional furnace to about 500 F. The coils will thenhave a fine coating of SiO which provides the necessary insulation andprotects the coils during encapsulation. The silicone oil may be ofcommercial gradeand the weight percent of silicone is not consideredcritical.

Another method, which has been found particularly suitable for coatingthe coils of the disclosed device with a refractory utilizes acommercial acrylic paint which includes titania (TiO Titania is used incommercial paint to add opacity. A suitable acrylic paint is a watersoluble vinyl acrylic copolymer resin having TiO suspended therein soldby Sears, Roebuck and Company. A typical formulation, by weight, forthis paint is as follows:

. Titania 25.57: Silicates l3.3'/1 Vinyl acrylic resins 14.77: Water46.5% Total The coils are dipped inthe acrylic paint,- permitted to dryand then heated in a conventional furnace at a temperature of betweenabout 500 and 550 F. until the acrylic resin is substantiallyvolatilized. The coils then include a thin coating of titania. It hasalso been found that other refractories may also be utilized, includingM 0 MgO, Zr0 and mullite, which is A1 0 SiO As described above, thecoils 24 are supported within face 32 which is secured to a cylindricalsupporting sur- 7 face in the engine efficiency system, such as anautomotive ignition coil. In this location, the ignition coil is asource of pulsating DC current, inducing a current 24. It has now beendiscovered that the aluminum body 30 substantially improves theefficiency of the system, apparently because the aluminum body collectsor concentrates the electric field. In the engine efficiency system, thecoils must be isolated electrically and insulated from the engine andsystem. The powdered refractory provides the necessary insulation andprevents surface washing of the copper during encapsulation.

As described above, the method of this invention is not limited to thespecific materials. The preferred embodiment of the device includescopper coils encapsulated in an aluminum body. A suitable material forthe coils is an uncoated bus bar wire, which is commercially purecopper. Copper melts at 1,98 1 F., which is above the meltingtemperature of aluminum. A suitable material for the body is commercial319 aluminum, which includes 4 percent by weight copper and 6 percent byweight silicon. The aluminum melts at between l,050 and l,075 F. and thenormal pouring temperature of commercial 319 aluminum is l,350 F. Atthese temperatures, however, the molten aluminum would wash the surfaceof the copper wires, partially dissolving the copper and possiblybreaking electrical contact. The coating of the wires with a powderedrefractory then protects the coils and provides the necessary electricalinsulation.

I claim:

l. A method of encapsulating a copper coil in an aluminum body,comprising:

a. coating a copper coil with a refractory powder suspended in asubstantially volatilizable fluid organic carrier, I

b. heating the coil to volatilize said organic carrier,

- above the volatilization temperature of said fluid organiccarrier,,but below the melting temperature of said copper coil, leavinga residue of said refractory powder on said coil, i c. potting said coilcoated with said powdered refractory in aluminum by pouring moltenaluminum around said coil, and

d. cooling the aluminum, thereby forming an aluminum body encapsulatingsaid coil.

2. The method defined in claim 1, including coiling a copper wire aroundan aluminum arbor, thereby forming said copper coil.

3. The method defined in claim 1, wherein said liquid organic carrier isa commercial acrylic paint having powdered TiO suspended therein,including dipping said coil in said acrylic paint and heating saidcoated coil to a temperature between about 500 and 550 F., therebyvolatilizing the acrylic binder and leaving a thin coating of powderedTiO 4. The method defined in claim 1, characterized in that said organiccarrier is a silicone oil having pow.- dered Si0 suspended therein,including heating said coil to a temperature above about 500? F.,thereby volatilizing said oiland leaving aresidue of SiO, on said coil.

5. The method defined in claim 1, including inserting said coilcoatedwith said refractory in a mold having the preferred internalconfiguration and pouring molten aluminum into said mold, wherein saidrefractory prevents washing of the copper coil.

6. A method of encapsulating a plurality of conductive coils inaluminum, said coils having a melting temperature above the meltingtemperature of aluminum and electrically insulated from each other,comprising the steps of:

a. coiling conductive wire around two aluminum arbors thereby formingtwo separate conductive coils, one on each of said arbors,

b. coating each of said coils with a thin layer of powdered refractory,

c. inserting said coils, while still on said arbors, intov a mold inspaced relation,

d. pouring molten aluminum into said mold, around said coils, whereinsaid refractory prevents washing of the coils, and

I e. cooling said aluminum, thereby forming an aluminum article havingconductive coils encapsulated therein.

7. The method defined in claim 6, wherein said conductive coils are eachcoated with a refractory selected from the group consisting of SiO TiOA1 0 MgO, SrO and mullite, by coating said coils with said refractorysuspended in a liquid organic carrier which is substantiallyvolatilizable at elevated temperatures and heating said coils above thevolatilization temperature of the binder, but below-the meltingtemperature of aluminum.

8. The method defined in claim 7, wherein said organic binder is a watersoluble acrylic and said coils are heated to a temperature above aboutQQQ F.

9. The method defined in claim 8, wherein said acrylic binder is acommercial paint having powdered TiO suspended therein, includingheating said coils to a temperature between about 500 and 550 F.,leaving a residue of powdered TiO on said coils.

10. The method defined in claim 7, wherein said organic carrier is asilicone oil having SiO suspended therein, including heating said coilsabove about 500 F ll. A method of encapsulating a plurality of conductive coils in a conductive metal having a melting temperature below themelting temperature of said coils and said coils electrically insulatedfrom each other, comprising the steps of:

a. coiling conductive wire around two cylindrical arbors, therebyforming two separate conductive coils, one on each of said arbors,

b. coating each of said coils with a thin layer of powdered refractoryby first coating said coils with a refractory suspended in avolatilizable carrier and heating said coils to volatilize said carrier,leaving a residue coating of said refractory,

c. inserting said coils, while still on said arbors, into a mold inspaced relation,

d. pouring said metal in a molten state into said mold, around saidcoils, wherein said refractory prevents washing'of said coils, and

e. coolingsaid metal, thereby forming a metal article having conductivecoils encapsulated therein.

12. The method defined in claim 11, wherein said metal is aluminum andsaid coils are copper, including pouring said aluminum at about l350 F.

2. The method defined in claim 1, including coiling a copper wire aroundan aluminum arbor, thereby forming said copper coil.
 3. The methoddefined in claim 1, wherein said liquid organic carrier is a commercialacrylic paint having powdered TiO2 suspended therein, including dippingsaid coil in said acrylic paint and heating said coated coil to atemperature between about 500* and 550* F., thereby volatilizing theacrylic binder and leaving a thin coating of powdered TiO2.
 4. Themethod defined in claim 1, characterized in that said organic carrier isa silicone oil having powdered SiO2 suspended therein, including heatingsaid coil to a temperature above about 500* F., thereby volatilizingsaid oil and leaving a residue of SiO2 on said coil.
 5. The methoddefined in claim 1, including inserting said coil coated with saidrefractory in a mold having the preferred internal configuration andpouring molten aluminum into said mold, wherein said refractory preventswashing of the copper coil.
 6. A method of encapsulating a plurality ofconductive coils in aluminum, said coils having a melting temperatureabove the melting temperature of aluminum and electrically insulatedfrom each other, comprising the steps of: a. coiling conductive wirearound two aluminum arbors thereby forming two separate conductivecoils, one on each of said arbors, b. coating each of said coils with athin layer of powdered refractory, c. inserting said coils, while stillon said arbors, into a mold in spaced relation, d. pouring moltenaluminum into said mold, around said coils, wherein said refractoryprevents washing of the coils, and e. cooling said aluminum, therebyforming an aluminum article having conductive coils encapsulatedtherein.
 7. The method defined in claim 6, wherein said conductive coilsare each coated with a refractory selected from the group consisting ofSiO2, TiO2, Al2O3, MgO, SrO2 and mullite, by coating said coils withsaid refractory suspended in a liquid organic carrier which issubstantially volatilizable at elevated temperatures and heating saidcoils above the volatilization temperature of the binder, but below themelting temperature of aluminum.
 8. The method defineD in claim 7,wherein said organic binder is a water soluble acrylic and said coilsare heated to a temperature above about 500* F.
 9. The method defined inclaim 8, wherein said acrylic binder is a commercial paint havingpowdered TiO2 suspended therein, including heating said coils to atemperature between about 500* and 550* F., leaving a residue ofpowdered TiO2 on said coils.
 10. The method defined in claim 7, whereinsaid organic carrier is a silicone oil having SiO2 suspended therein,including heating said coils above about 500* F.
 11. A method ofencapsulating a plurality of conductive coils in a conductive metalhaving a melting temperature below the melting temperature of said coilsand said coils electrically insulated from each other, comprising thesteps of: a. coiling conductive wire around two cylindrical arbors,thereby forming two separate conductive coils, one on each of saidarbors, b. coating each of said coils with a thin layer of powderedrefractory by first coating said coils with a refractory suspended in avolatilizable carrier and heating said coils to volatilize said carrier,leaving a residue coating of said refractory, c. inserting said coils,while still on said arbors, into a mold in spaced relation, d. pouringsaid metal in a molten state into said mold, around said coils, whereinsaid refractory prevents washing of said coils, and e. cooling saidmetal, thereby forming a metal article having conductive coilsencapsulated therein.
 12. The method defined in claim 11, wherein saidmetal is aluminum and said coils are copper, including pouring saidaluminum at about 1350* F.